you(modders) can change only hairs for players and add beards for now,but maybe if someone check Faces that got updated in november with faces from pirated version of fifa 18,where their faces are not original"fake"(brighton,huddersfield,andre silva)to see the differences in files maybe someone will figure out how to Mod player faces(fake faces)?
If the question is stupid sorry
Hey aNuke I was getting the same error as you, but the trick is go into the fifa 18 folder and delete the ModData folder, and then fresh instal from zip both the editor and the mod manager. Worked for me. Let me know how you go.